Aluminium salts are used as the active
antiperspirant agent in underarm
cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of
breast cancer in the upper outer quadrant of the breast together with reports of
genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of
breast cancer.
Aluminium is known to have a genotoxic profile, capable of causing both
DNA alterations and epigenetic effects, and this would be consistent with a potential role in
breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in
breast cancer and its action, dependent on intracellular receptors which function as
ligand-activated zinc finger
transcription factors, suggests one possible point of interference from
aluminium. Results reported here demonstrate that
aluminium in the form of
aluminium chloride or
aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human
breast cancer cells both in terms of
ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds
aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of
aluminium exposure and whether
aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to
antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of
breast cancer.